I think Dan John said in one of his articles once "If you want to get better at throwing, then throw..." (pardon if I did not get the quote right). But that applies to anything from OLY, to Hockey, to Chess, to whatever. If you want to lift heavy....you lift heavy. Cross training is always good...but will not max out one goal...you may give up endurance for a while, but that is not your goal at this time.